Fuel burner control system



May 1945. R. w. DE LANCEY 2,375,900

FUEL BURNER CONTROL SYSTEM Filed June 25, 1942 3 Sheets-Sheet 1 INVENTOR Ralph W. DeLonceg AII'TORNEY R. w. DE LANCEY FUEL BURNER CONTROL SYSTEM J May 15, 1945. 2,375,900

Filed June 25, 1942 3 Sheets-Sheet 2 +21 INVENTOR Ranch W. DeLance ATTORNEY y 1945- R. DE LANCEY 2,375,900

FUEL BURNER CONTROL SYSTEM Filed June 25, 1942 s Sheets-Sheet s INVENTOR RALPH W DELn/vcEY ATTO R N EY Patented May 15, 1945 FUEL BURNER CONTROL SYSTEM Ralph W. De Lancey, Meriden, Conn, assignor to the. Miller Company, Meriden, Conm, a corporation of Connecticut Application June 25', 1942, Serial No. 448,385

11 Claims.

The present invention relates to fuel burner control systems, and is more particularly directed toward control systems for vaporizing type oil burners.

Vaporizing or pot type oil burners must always be supplied with some means of obtaining, at the time it is desired to start the high fire operation, an ignition of the fuel while it is in the liquid state. In commercial apparatus ignition has generally included the use of either a gas pilot, or an oil pilot.

The present invention relates to a fuelcontrolling system wherein electrical ignition is employed to start combustion in the burner, whereby vaporizing burner operation may be fully automatic and analogous to gun type or rptary burner operation. Electrical ignition makes it possible to dispense with the expense of gas ignition and troubles which may be incident to the use of low flame pilots over long periods.

The flow of fuel to vaporizing burners is generally under the control of a metering valveforming part of the constant level valve structure and arranged so that the metering valve will be opened under the control of a room thermostat, or manually, or by a combination manual and thermal means to allow a measured flow of fuel to reach the burner. Where flow of the fuel is under the control of a thermo-electrically operated valve, this valve has a time delaying funccuitis closed.

tion which causes the valve to open slowly after a predetermined time so that there is no sudden rush of fuel into the burner.

The present invention contemplates that the high tension electric spark will be applied to the vaporizer of the burner for an appreciable time prior to the arrival of the oil film on the vaporizer opposite the electrode, thereby making it possible to locally preheat an area in the vaporizer so that when the oil wets the surface of the vaporizer by capillary attraction, quick and certain ignition is possible. Where the operation is entirely automatic and the oil. valve opened by a time delay thermo-electric motor, it is contemplated that the application of the electric ignition will also be under the control of the thermo-electric motor having a different time constant than the valve, so that the ignition potential will preferably precede the arrival of the fuel.

Where the vaporizing burner is of the type requiring a blast of air to maintain proper combustion, the blower motor for supplyin this blast of air need not be operated when the burner is shut down, and'according to the present inven- Accordin to the present invention the timer which controls the starting of the ignition and the starting of the operation of the blower is arranged so that the ignition will be turned off after a few minutes operation and the blower will be continued in operation as long as the fuel valve is held open and for some time after, so as to provide air to consume all residues i the vaporizer, whereby the vaporizer is left clean until another high fire period is required. v

By reason of momentary power failures or manipulation of the room thermostat the proper operation of the burner may have been interrupted in such a way that the fire goes out while there .is still some fuel in the vaporizer.

According to the present invention provision is made to reestablish ignition soon after the power is restored, or the thermostat turned up to where heat is called for. To accomplish this the timer is so arranged that after a very short period of cooling from the high temperature to which it is normally maintained during operation the timer regains control of the ignition so that when the timer is again reheated ignition is reestablished.

Oil burners of the type to which the present invention is directed are used not only with steam furnaces or hot air or hot water furnaces without blowers or pumps, but also with furnaces designed for forced air circulation or for forced hot water circulation. The present invention contemplates that the timing mechanism which controls the sequence of operation of fuel supply, ignition and air for combustion (where necessary) may also be used to time the operation of the blower or pump used for circulating the air or hot water as the case may be. This timer may be arranged to start the operation of a circulatin motor at the proper time after'the burner has been brought into full operation so that hot air may be circulated as soon as available, and this operation may be continued for a suitable length of time after the burner operation has ceased so as to abstract a portion of. the residual heat in the furnace.

Other and further objects will hereinafter appear as the description proceeds.

The accompanying drawings show, for purposes of illustrating the present invention, two embodiments in which the invention may take form, it being understood that the drawings are illustrative of the invention rather than limiting the same.

In these drawings:

Figure 1 is -a side elevational view of a vaporizing type oil burner with associated controls;

Figure 2 is a top plan view of the structure of Figure 1;

Figure 3 is a sectional view taken on the line 3-3 of Figures 2 and 6 illustrating the timer control for the ignition;

Figure 4 is an elevational view with parts in section taken on the lines 4-4 of Figures 2, 3 and 6 illustrating the timer for the ignition as well as for the motors;

Figure 5 is a sectional view taken on the line 5--5 of Figures 4 and 6;

Figure 6 is a top plan view with parts in section on the line 6-6 of Figures 3, 4 and 5;

Figures 7a to 7d, inclusive, are fragmentary views illustrating the timer parts at different stages, Figure 7a being the off position, Figure 7b the position after a very short interval sulficient to start ignition, Figure 7c a later period where the vaporizer blower is in operation and ignition being continued, and Figure 7d being the normal running position for the burner;

Figures 8 and 9 are diagrammatic illustrations showing the operation of a circulating hot water furnace and of a hot air furnace, respectively, by the burner;

Figure 10 is a wiring diagram for a system with thermally controlled oil valve; and

Figure 11 is a wiring diagram'for a system with manually controlled oil valve.

Figures 1 and 2 illustrate a complete oil burner unit designed for installation in a furnace. The parts are all secured to a box-like body or conduit I supported on legs I I, ll.

Oil for operating the burner is received (through pipingnot shown) by a combined constant level valve and metering valve indicated generally at I2. This valve is designed to provide a controlled flow of oil for high fire only. The oil passes through .piping indicated at |3, M to the vaporizer or pot of the burner, designated generally' by the reference character l6. Such burners are designed to operate with a pool of oil indicated at IT. Air for combustion is supplied by a blower motor I8 operating a fan 9 which blows air through the conduit l0 and into the vaporizer to maintain a forced draft.

The valve stem of a thermal metering valve incorporated in the structure I2 is indicated in Figure at 20. This valve stem is under the control of a bimetallic thermostat 2| heated by a coil 22 which is supplied with low voltage current through a transformer 23 under the control of a room thermostat-24 (or manual switch as referred to below) and a limit switch 25, as usual in remote controlled, thermally operated oil valves. The purpose of this arrangement is to supply a metered flow of fuel to the burner when the room thermostat calls for heat and the limit switch is closed, and no fuel for pilot operation. Thermostatically operated metering valves of this type have a delay in the valve opening due to the time required for heating the thermostat.

Further'reference to Figure 10'will show that the transformer 23 also supplies current to a circuit in parallel with the heater 22, and this parallel circuit includes a heater 26 placed below a bimetallic thermostat 21 preferably coiled to a clock spring form, as shown more in detail in Figures 3, 4 and 6. The bimetallic element 21 acts as a thermal motor with predetermined time delay to operate a shaft 28 in a clockwise direction as viewed in Figures 3, 7a to 7d, inclusive, and Figure 10. The shaft 28 is mounted near the top of a frame 29 of U-shaped cross section in horizontal planes, as shown more clearly in Figures 3 to 6. This timer frame is mounted on the top of the conduit ID at the end remote from the burner so as to be outside the furnace, and the timer is enclosed in a protecting cover 3|).

The turning of the shaft 28 of the thermal motor is utilized to control, in timed sequence, the ignition for the burner, the starting of the fan, and, where desired, the operation of the circulator, and the drawings show in detail a convenient form of construction for carrying out these operations in the desired sequence. To operate the igniter the shaft 28 is here shown as being provided with a mutilated gear 3|. The frame 29 carries a lever 32 pivoted at 33 and extending nearly up to the gear 3|. The upper end of the lever 32 carries a spring member 34 bowed as indicated at 34' whose upper end 35 is shaped to enter in between two adjacent teeth of the gear 3|. The movement of the spring is limited to sliding only by a screw 34". The lower end of the lever 32 carries an adjustable screw 36 adapted to actuate a very sensitive, or micro, switch 31, this switch being of the type which is biased to open position so that it tends to shift the lever 32 in a counterclockwise direction as viewed in Figure 3. A screw 39 carried on a bracket 38 holds the lever in proper position so it cannot fall away from the gear teeth. The parts just described are normally arranged so that the switch 31 is open and the end of the lever 34 just to the right of the line connecting the centers 33 and 28, the end 35 of the spring 34'being held between two adjacent teeth by its bowed shape at 34. As soon as the bimetallic thermostat 21 has been heated suificiently to start moving the shaft 28 it brings the tooth to the right of the end 35 of spring 34 against this spring and tends to move the lever 32 in a counterclockwise direction, this movement being indicated by the difference in the position of the parts in Figures 7a and 1b. This very slight movement at the leverage available is sufficient to close the switch 31, and this switch will remain closed so long as the teeth on the gear 3| engage the spring 34 and the gear is moving in the clockwise direction.

One side of the switch 31 is connected to the power line by a lead 40, while the other side is connected by a lead 4| with the primary 42 of a sparking transformer connected to the other side of the line by a lead 43, as indicated in Figure 10. The secondary 44 of the transformer which is adapted to deliver a high voltage, preferably 10,000 volts, is connected by a high tension lead 45 with an electrode 46 which extends down into the vaporizer. This electrode terminates adjacent the surface of the vaporizer, preferably above the upper oil level as described more fully in my application Serial No. 435,690, filed March 21, 1942.

Owing to the slight movement required of thermostat 21 it is possible to close the ignition circuit and establish the spark in a short time after the room thermostat has called for heat. The delay in obtaining the spark may be in the neighbo-rhood. of to seconds, and this delay is' usually less than the delay required to operate the metering valve so as to supply oil to the burner, The delay in oil flow may be in the order of 40 to seconds. The. sparking of the electrode therefore continues for a substantial period of time before the oil reaches the vaporizer and climbs by capillary attraction to the surface of the vaporizer opposite the electrode. This makes it possible for the electrode to cause local heating of the surface of the vaporizer. This localized area will usually include minute residual carbon deposits, The heating of this area of the vaporizer facilitates vaporizing the film. of oil as it climbs by capillarity over the vaporizer surface and very quickly establishes ignition. The time required for the teeth of the gear 3| to pass beyond the end of the lever, so that ignition current is discontinued, is preferably long enough to maintain an arc during the entire time required by the metering valve to raise the oil level to the maximum. The arc will start combustion even thoughthe arrival of oil near enough for ignition is delayed until after the blower has started.

The shaft 28 of the timer motor carries at the right, as shown in Figures 4 and 6, a cam memher 5!] having a small diameter portion 5i and a large diameter portion 532. The small diameter portion 5B is normally in engagement with the upper end 53 of a lever 5d pivoted at near the bottom of the frame 25. This lever is urged to the left by an insulated contact spring 56 bearing on insulated adjusting screw 5'! so as to bear against the cam. When the thermostat 2's has shifted the shaft 28 through an angle somewhat greater than that required to establish ignition, it brings the larger diameter portion 52 of the cam 59 against the end 53 of lever arm 54 and swings this lever against the tension of contact spring 55 bringing this spring against a fixed contact 58. carried by an insulator 59 secured to the side of the frame 29 and provided with terminals 60 and 6|. One of these terminals, for example, the terminal Bl is connected by wire .62 with one side of the power line, while the other terminal, such as 68, is connected by a wire 63 with the blower motor l8 which drives the fan 19. In order to limit the angular movement of the shaft 28 the cam 58 is provided with a projection M adapted to push the lever 54 against a stop screw 65, Ordinarily these parts do not come into engagement.

It will thus be seen that shortly after the establishment of ignition the circuit has been closed to the blower motor so that air for combustion is supplied to the vaporizer. The time required after the room thermostat calls for heat to start the blower motor it in operation may be of the order of 60 to seconds. The position of the parts at this time is indicated diagramamtically in Figure 7c. After the establishment of ignition and of forced draft, the thermal motor in the timer continues to turn the shaft 28 and after a period of about a or 5 minutes the last tooth on the multilated gear is moved beyond the end of the spring 35, as indicated in Figure 7d. This permits the switch 31 to open and discontinue the ignition. It, however, has no effect upon the operation of the forced draft blower.

Should the limit switch open or there be a momentary power failure, or should one manipulate the room thermostat so that it does not call for heat, the oil valve will start to close and the The contacts 55 and 53 are thermal motor in the timer will start back toward the idle position. This will cause the teeth on the gear 3| to come opposite the end of the spring 34, but, owing to the-direction of motion being opposite what it was when the ignition circuit was closed, this causes no effect on the ignition circuit. During this interval it is possible that the flame could have gone out in. the burner. Should the room thermostat be moved again to call for heat, the limit switch reclose, or power be restored, flooding of the burner is avoided, because the reheating of the timer thermostat 2! causes the gear to move again in the clockwise direction, reclosing' the ignition switch. and reestablishing ignition.

In normal operation the room thermostat becomes satisfied and deenergizes the heater coils for the oil valve and the timer and the parts return to normal idle position. It takes some time for the oil valve to close, and, hence oil flows for an appreciable time after the room thermostat has been satisfied. The return of the shaft 28 to normal position requires a greater length of time than required for the thermostat to shut off the oil flow and for the consumption of the: oil remaining in the vaporizer. In this way it is possible to continue the blast of air into the vaporizer for some times after all the oil should be consumed, thus making it certain that the flame in the vaporizer has become extinguished by lack of fuel before the air supply is discontinued. This results in clean combustion and the burning up of all the burnable residues in the vaporizer. As an example of typical timing for these operations it is not unusual for the flame to continue for about three minutes after the room thermostat has been satisfied and operation of the blower for a period of about six minutes after the room thermostat has been satisfied will insure cleaning up of the residues and the extinguishment of the flame.

The drawings also illustrate, in addition to the sequence control for igintion and blower motor operation, the control of the motor used for circulating hot water in a hot water system, or blowing hot air in a hot air system. To carry out this operation the shaft 28 also carries a cam 10 generally the same as the cam 50 (but without stop extension 64). Cam ll) cooperates with a switch arm ll similar to the switch arm 54 and adapted to close the circuit between contacts 12 and 13. (similar to contacts 56 and 58). One of these contacts is connected to one side of the line and the other to a motor 74. This motor may, as shown in Figure 8, operate a circulating pump for a hot water system, or, as shown in Figure 9, operate a blower for circulating air through a hot air furnace.

The cam 10 is preferably timed to come into action shortly after the blower motor I B so as give the burner time for heating the furnace.

In heating systems which employ a manually operated switch to initiate the operation of the thermal metering valve, parts may all be as above described in detail, a manually operated switch being substituted for the room thermostat.

Oil burners of the type previously referred to are at times under the control of a manual metering valve instead of a thermal metering valve. Figure 11 diagrammatically shows a manual metering valve stem at under the control of a lever 80 operated by a pin 80" carried by a shaft.

8! adapted to be turned by a knob 82. This shaft carries an insulated contact 83 adapted to bridge two fixed contacts 84 and 85. These contacts are in the circuit of the low tension side of a transformer 86 and control the energization of a relay 8! and a heater coil 26a similar to coil 28. Contacts 68, 88 of the relay 8'! are normal open and are in series with a normally closed switch 89 in the circuit of the primary 90 of the ignition transformer 9|. The timer operated by the heater coil 26a and bimetallic element 21a may be the same as that described above, except that the ignition control employs a cam 92 which normally holds an arm 93 to the right so as to hold the switch 89 closed. After the timer 'has operated the shaft 28 a predetermined amount, the low part 94 of the cam is brought opposite the upper end of the arm 93 permitting the switch lever to open and discontinue the ignition. This arrangement has the same cycle of operations as the one above described in detail.

From the foregoing it will be apparent that pilot ignition either by oil or gas is rendered unnecessary, and the oil burner operation may be made completely automatic with sequence control of supply of fuel, initiation of ignition and supply of air for combustion, together with the desired operation of the circulator motor,

It is obvious that the invention may be embodied in many forms and constructions within the scope of the claims and I wish it to be understood that the particular forms shown are but a few of the many forms. Various modifications and changes being possible, I do not otherwise limit myself in any way with respect thereto.

What is claimed is:

1. In a fuel burner control system, a gravity fed liquid fuel burner, a fuel supply line for the burner including a normally closed fuel valve, an electrically heated, thermostatically operated device for opening and closin the valve and having a predetermined time element during open ing and closing, a power supply line, ignition means including a sparking electrode, a high tension transformer and a normally open ignition switch for connecting the ignition means to the power supply line, a motor driven blower to supply air to the burner, a normally open power lineconnected blower motor switch for controlling the blower motor, and an automatic thermo-electric timer structurally independent of the valve operating device but energized concurrently with it and including means acting in predetermined sequence and time spacing relation to the open ing of the valve to close the ignition switch and then the blower motor switch and then open the ignition switch and on deenergization to open the blower motor switch subsequent to the completion of the closing of the valve.

2. The system of claim 1, wherein the timer includes means to regain control of the ignition switch after a period of deenergization insufficient to stop the blower motor so that upon immediate reenergization the ignition switch is reclosed.

3. In a fuel burner control system, a gravity fed vaporizing type liquid fuel burner, a spark electrode in the burner, a circuit for the electrode including a spark coil and a normally open ignition switch, means including a thermo-electrically operated and timed fuel valve controlling the supply of fuel. to the burner, and a single thermo-electrically operated timer in parallel with the thermo electric operator of the fuel valve and continuously energized concurrently therewith and including means which closes the ignition switch after a predetermined interval but before the fuel valve has admitted sufllcient fuel to bring the fuel level in the burner to the normal operating level and holds it closed for a predetermined interval, and thereafter releases the ignition switch to allow the latter to open.

4. In a fuel burner control system, a gravity fed vaporizing type liquid fuel burner, an ignition device in the burner, a circuit for the ignition device including a normally open ignition switch, means including an electrically operated fuel valve controlling the supply of fuel to the burner, and a single thermo-electrically operated timer in parallel with the electric operator of the fuel valve and continuously energized concurrently therewith and including means which closes the ignition switch after a predetermined interval but before the fuel valve has admitted sufficient fuel to bring the fuel level in the burner to the normal operating level and holds it closed for a predetermined interval, and thereafter releases the ignition switch to allow the latter to open.

, 5. A system such as claimed in claim 4, having means whereby when the ignition switch timer returns toward normal position on deenergization it reengages the ignition switch so that upon reenergization of the timer the ignition switch is reclosed.

6. In a fuel burner control system, a gravity fed vaporizing type liquid fuel burner, an ignition device in the burner, a circuit for the ignition device including a normally open ignition switch, means including an electrically operated fuel valve controlling the supply of fuel to the burner, an electrically operated blower for supplying a stream of air to the burner, a blower control switch, and a single thermo-electrically operated timer in parallel with the electric operator of the fuel valve and continuously energized concurrently therewith and including means which closes the ignition switch after a predetermined interval but before the fuel valve has admitted sufficient fuel to bring the fuel level in the burner to the normal operating level and holds the ignition switch closed for a predetermined interval and then releases it to allow it to open and which closes the blower control switch a predetermined time after the closing of the ignition switch, and holds it closed so long as the timer is energized and for a predetermined cooling off period after it has been deenergized.

7. In a fuel burner control system, a gravity fed liquid fuel burner, a fuel supply line for the burner including a normally closed fuel valve and a thermo-electric valve controller having a delayed opening and closing operation, a power supply line, ignition means including a sparking electrode, a high tension transformer and a nor-- mally open ignition switch for connecting the ignition means to the power supply line, a motor driven blower to supply air to the burner, a normally open blower motor switch for connecting the blower motor to the power supply line, and a thermo-electric timer energized concurrently with the valvecontroller and including means acting on energization in predetermined sequence and time spacing to close the ignition switch and then the blower motor switch and then open the ignition switch and on deenergization to open the blower motor switch subsequent to the completion of the closing of the valve.

8. The system of claim 7, wherein the timer includes means to regain control of the ignition switch after a period of deenergization insufiicient to stop the blower motor so that upon immediate reenergization th ignition switch is reclosed.

' 9. In combination, a power supply, a furnace for heatin remote regions by a circulating fluid and having a motor operated pump for maintaining a forced circulation of said fiuid, a pump motor switch for connecting the pump motor to the power supply, a liquid fuel burner, a fuel control valve, an electrically heated, thermostatically operated fuel valve control means to move the valve between fully open and fully closed positions to regulate the flow of fuel at a predetermined rate or to stop fuel flow and requiring a substantial interval of time after energization to attain that rate and after deenergization to stop fuel flow, timing means connected in parallel with the heater of the fuel control means and having a timing rate with a predetermined time relation with the timing rate of the heater, electric ignition means controlled by the timing means, a normally open power-supply-connected ignition switch, a motor driven blower to supply air to the burner, a normally open power-supply-connected blower motor switch for controlling the blower motor, said timer including means acting on energization in predetermined sequence and time spacing to first close the ignition switch, then close the blower motor switch, then close the pump motor switch and to open the ignition switch subsequent to the closing of the blower motor switch, and acting on deenergization to open the motor switches subsequent to the completion of the closing of the valve.

10. In combination, a furnace for heating remote regions by a circulating fluid and having a motor operated pump for maintaining a forced circulation of said fluid, a liquid fuel burner, a fuel control valve, an electrically heated, thermostatically operated fuel valve control means to move the valve between fully open and fully closed positions to regulate flow of fuel at a predetermined rate or stop fuel flow and requiring a substantial interval of time after energization to attain that rate or after deenergization to 5 electric ignition means controlled by the timing means and operable only during a period substantially that required to bring the fuel level to the normal operating level, a power operated blower for supplying the burner air for combustion,

means controlled by the timing means to start the blower during the period the ignition means is in operation and maintain the blower in operation until after the fuel valve is closed, and means controlled by the timing means to start the pump 5 after the said firing rate has continued for a predetermined time and for stopping the pump at substantially the same time as the blower.

11. In a fuel burner control system, a gravity fed vaporizing type liquid fuel burner, a fuel control valve, an electrically heated, thermostati-.

cally operated fuel valve control means to move the valve between fully open and fully closed positions to regulate flow of fuel at a predetermined rate or stop fuel flow and requiring a substantial interval of time after energization to attain that rate or after deenergization to stop fuel flow, electric ignition means, a thermo-electric timer connected in parallel with the heater for the fuel control means so as to be operated concurrently, the timer including means operating the ignition means during the initial period of fuel flow and then disconnecting it, a power operated blower for supplying the burner air for combustion, and timer controlled means to start the blower during the period the inition means is in operation and prior to the attainment by the timer of its maximum distortion under heat, the timer requiring a longer period to cool off in an amount to stop the blower than the heater for the fuel control means to effect the closing of the fuel valve whereby the blower may be maintained in operation for a predetermined time after the fuel valve is closed.

RALPH W. DE LANCEY. 

